We only carry 25.4 mm and 26.0 mm shims since those are the two most common handlebar sizes outside of 31.8 mm. 

There are other manufacturers that make shims for a variety of other size handlebars. 

Check your local bike shop or Amazon and you should be able to find what you need. 

Look for a shim with an inner diameter that matches your handlebar exactly, and an outer diameter of 31.8 mm.